ATLANTA, Georgia (CNN) -- Police are looking for a man described as a "person of interest," in the case of a 24-year-old woman who has been missing in the north Georgia mountains since New Year's Day, a Union County Sheriff's spokeswoman told reporters Thursday.
Several eyewitnesses saw Gary Michael Hilton, 61, and his reddish dog with Meredith Emerson before she disappeared, investigator Kimberly Verdone said.
Verdone earlier described the man as about 5 feet, 10 inches tall and weighing about 160 pounds, and said he was seen with Emerson on "multiple occasions" on Tuesday along the Freeman Trail on Blood Mountain.
Emerson, originally from Colorado, was hiking the trail with her black Labrador retriever on Tuesday, Verdone said.
She was reported missing Wednesday.
"At one time they were seen talking and let the dogs run loose; the dogs ran up the mountain, and they followed them afterwards," she said of the man and Emerson.
She also described the man as having "bad" or "no teeth," and wearing a yellow jacket with a "large, older backpack," that someone would "use for a couple of days," she said.
He also had a "sheath of some sorts" attached to one leg, but Verdone said she did not know what it contained. Watch Verdone describe man police want to find »
The man's dog responded to the name "Dandy," not "Danny" as police originally reported, she said.
One eyewitness noted the license plate on a 2001 Ford Astro minivan registered to Hilton in DeKalb County, Georgia, Verdone said. The Georgia Bureau of Investigation found a second white 1996 Astro van registered to Hilton, also in DeKalb County. Police released the tag numbers and asked people to be on the lookout for either vehicle, she said.
Authorities in DeKalb County, however, said Hilton is not believed to reside in the county.
Police and dozens of volunteers hiked into the cold mountains for a second day Thursday to search for Emerson, a University of Georgia alumna, Verdone said. Emerson family spokeswoman Peggy Bailey said the girl's father was among the volunteers.
Authorities are making "every effort to find Meredith," Verdone said. The search Thursday would continue until dusk, she said.
A Georgia State Police helicopter was also flying over the area, and the Georgia Bureau of Investigation was also assisting in the search, Verdone said.
At an earlier Thursday news conference, Verdone said police have confirmed that a water bottle and a leash found in the area belonged to Emerson. The young woman's vehicle also was found at the head of the 6-mile Freedom Trail -- which is part of the Appalachian Trail -- Verdone told CNN Wednesday.
Emerson's roommate, Julia Karrenbauer, told CNN Thursday that Emerson's sunglasses and mittens were found in the area, as was a baton.
Verdone did not confirm those reports. She said Emerson, whom she described as "familiar with hiking," had been dressed for the cold weather on Tuesday.
Bailey described the blonde, 5-foot-4, 120-pound woman as "athletic," "feisty" and "level-headed."
"Meredith Emerson could do anything," she said. "I'm praying hard."
Bailey said Emerson's parents flew to Georgia Wednesday night from Colorado. They are "devastated and frightened," she said. "They're waiting as we all are."
Verdone urged people with information regarding the young woman or the "person of interest" to call (706) 439 - 6038. E-mail to a friend
CNN's Marylynn Ryan and Michael Phelan contributed to this report.
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